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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16

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NASA NTRS1990

A dynamic motion simulator for future European docking systems

Europe's first confrontation with docking in space will require extensive testing to verify design and performance and to qualify hardware. For this purpose, a Docking Dynamics Test Facility (DDTF) was developed. It allows reproduction on the ground of the same impact loads and relative motion dynamics which would occur in space during docking. It uses a 9 degree of freedom, servo-motion system, controlled by a real time computer, which simulates the docking spacecraft in a zero-g environment. The test technique involves and active loop based on six axis force and torque detection, a mathematical simulation of individual spacecraft dynamics, and a 9 degree of freedom servomotion of which 3 DOFs allow extension of the kinematic range to 5 m. The configuration was checked out by closed loop tests involving spacecraft control models and real sensor hardware. The test facility at present has an extensive configuration that allows evaluation of both proximity control and docking systems. It provides a versatile tool to verify system design, hardware items and performance capabilities in the ongoing HERMES and COLUMBUS programs. The test system is described and its capabilities are summarized.

Brondino, G.↗

NASA NTRS1990

USSR Space Life Sciences Digest, issue 25

This is the twenty-fifth issue of NASA's Space Life Sciences Digest. It contains abstracts of 42 journal papers or book chapters published in Russian and of 3 Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. The abstracts in this issue have been identified as relevant to 26 areas of space biology and medicine. These areas include: adaptation, body fluids, botany, cardiovascular and respiratory systems, developmental biology, endocrinology, enzymology, equipment and instrumentation, exobiology, gravitational biology, habitability and environmental effects, human performance, immunology, life support systems, man-machine systems, mathematical modeling, metabolism, microbiology, musculoskeletal system, neurophysiology, nutrition, operational medicine, psychology, radiobiology, reproductive system, and space biology and medicine.

Hooke, Lydia Razran↗

NASA NTRS1990

Airborne lidar/radiometric measurements of cirrus cloud parameters and their application to LOWTRAN radiance evaluations

SRI has assembled an airborne lidar/radiometric instrumentation suite for mapping cirrus cloud distribution and analyzing cirrus cloud optical properties. Operation of upward viewing infrared radiometers from an airborne platform provides the optimum method of measuring high altitude cold cloud radiative properties with minimum interference from the thermal emission by the earth's surface and lower atmospheric components. Airborne installed sensors can also operate over large regional areas including water, urban, and mountain surfaces and above lower atmospheric convective clouds and haze layers. Currently available sensors installed on the SRI Queen Air aircraft are illustrated. Lidar and radiometric data records are processed for real time viewing on a color video screen. A cirrus cloud data example is presented as a black and white reproduction of a color display of data at the aircraft altitude of 12,000 ft, the 8 to 14 micron atmospheric radiation background was equivalent to a blackbody temperature of about -60 C and, therefore, the radiometer did not respond strongly to low density cirrus cloud concentrations detected by the lidar. Cloud blackbody temperatures (observed by radiometer) are shown plotted against midcloud temperatures (derived from lidar observed cloud heights and supporting temperature profiles) for data collected on 30 June and 28 July.

Uthe, Edward E.↗

NASA NTRS1990

Component model reduction via the projection and assembly method

This paper explains the projection and assembly model reduction method which has been used to derive reduced order component models for the Galileo spacecraft. Assembly of reduced order component models produces a reduced order system model which can then be used in multibody simulation codes for efficient run times. The methodology is explained and a proof is given showing the exact reproduction of selected significant system modes. Frequency bounds are obtained for all modes produced when the reduced order components are assembled. The projection and assembly method is demonstrated on two examples. The first example is a simplified model of the Galileo spacecraft, while the second example is the model of the Galileo spacecraft in its early mission configuration. When articulation of components is allowed, the method may not reproduce all system modes precisely. Remedies for this problem are suggested.

Kissel, Glen J.↗

NASA NTRS1990

Viscous computations using a direct solver

Laminar viscous flows over airfoils are investigated analytically, applying the flux-difference splitting scheme of Roe (1986) to solve the thin-layer Navier-Stokes equations. Central-difference discretization is used for the viscous terms, and a fully implicit implementation is employed to minimize the Reynolds-number effect on convergence. Results for flows at freestream Mach number 0.5 and Reynolds number 5000 over NACA0012 airfoils at angles of attack 0 and 3 deg are presented graphically and discussed in detail. Good agreement with previous calculations is obtained, with accurate reproduction of essential features despite the use of coarser meshes.

Venkatakrishnan, V.↗

NASA NTRS1989

The nematode C. elegans - A model animal system for the detection of genetic and developmental lesions

The effects of ionizing and nonionizing radiation effects on cell reproduction, differentiation, and mutation in vivo are studied using the nematode C. elegans. The relationships between fluence/dose and response and quality factor and linear energy transfer are analyzed. The data reveal that there is a complex repair pathway in the nematode and that mutants can be used to direct the sensitivity of the system to specific mutagens/radiation types.

Nelson, Gregory A.↗

NASA NTRS1990

Low-temperature Galactic fountains

Analytic and one- and two-dimensional hydrodynamic calculations are performed to determine whether or not the Galactic fountain model can explain observations of neutral gas in the Galactic halo. Galactic halo gasdynamics are examined, including thermal conduction, Galactic rotation, and Galactic fountains. Results are presented from numerical modeling of low-temperature Galactic fountains. It is found that the best reproduction of the observations is provided by a model near the transonic regime with a temperature and density at the base of the fountain of 300,000 K and 0.001/cu cm, respectively. The cooling time for the hot gas is 33 million yr and the time for newly formed clouds to return to the disk is 47 million yr, neglecting drag forces.

Houck, John C.↗

NASA NTRS1990

USSR Space Life Sciences Digest, issue 28

This is the twenty-eighth issue of NASA's Space Life Sciences Digest. It contains abstracts of 60 journal papers or book chapters published in Russian and of 3 Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. The abstracts in this issue have been identified as relevant to 20 areas of space biology and medicine. These areas include: adaptation, aviation medicine, botany, cardiovascular and respiratory systems, developmental biology, endocrinology, enzymology, equipment and instrumentation, hematology, human performance, immunology, life support systems, mathematical modeling, musculoskeletal system, neurophysiology, personnel selection, psychology, radiobiology, reproductive system, and space medicine.

Stone, Lydia Razran↗

NASA NTRS1990

An investigation of messy genetic algorithms

Genetic algorithms (GAs) are search procedures based on the mechanics of natural selection and natural genetics. They combine the use of string codings or artificial chromosomes and populations with the selective and juxtapositional power of reproduction and recombination to motivate a surprisingly powerful search heuristic in many problems. Despite their empirical success, there has been a long standing objection to the use of GAs in arbitrarily difficult problems. A new approach was launched. Results to a 30-bit, order-three-deception problem were obtained using a new type of genetic algorithm called a messy genetic algorithm (mGAs). Messy genetic algorithms combine the use of variable-length strings, a two-phase selection scheme, and messy genetic operators to effect a solution to the fixed-coding problem of standard simple GAs. The results of the study of mGAs in problems with nonuniform subfunction scale and size are presented. The mGA approach is summarized, both its operation and the theory of its use. Experiments on problems of varying scale, varying building-block size, and combined varying scale and size are presented.

Goldberg, David E.↗

NASA NTRS1991

Particulate impacts on the UHCRE cosmic ray experiment teflon covers: The ESA programme

The optical scanning equipment at the University of Kent Unit for Space Science consists of a 102.5 by 42.5 cm computer controlled motorized stage which has a reproduction accuracy of 30 microns over the entire area. This is used with an optical microscope connected to two charge coupled device video cameras which can be used to obtain stereo color images of any features found. A coordinate system can be defined on each cover by means of two or more reference marks which allow a feature to be located using different equipment such as a scanning electron microscope, providing two known marks can be found. By using back illumination, penetrating features can be found automatically, and their sizes, circularity, and positions logged for later revisiting either on the optical system or using a scanning electron microscope.

Mcdonnell, J. A. M.↗

NASA NTRS1991

From C/Mrkos to P/Halley: 30 years of cometary spectroscopy

An Atlas of Cometary Spectra was compiled, as a sequel to the well-known Atlas published by Swings and Haser in 1956. The new atlas comprises some 400 reproductions of cometary spectra secured in the world's largest observatories during the three decades or so from the passage of comet Mrkos 1957 V, for which the very first high-dispersion spectrum was obtained, to the return of Halley's comet. The illustrations refer to 40 different comet apparitions; they are grouped into a set of 186 loose 11 x 14 in. plates, while the texts, comments, and relevant data are given in a separate booklet. The main purpose of this atlas is to show in detail the tremendous progress which was achieved in cometary spectroscopy during the period covered, essentially thanks to the use of high-resolution coude spectrographs and large telescopes, the considerable extension of the observed wavelength range, and the advent of electronic detectors. It is divided into two parts. Part 1, which contains about two-thirds of the selected material, presents photographic spectra, while electronically recorded spectra covering the vacuum ultraviolet, through the optical, infrared, and radio regions appear in Part 2.

Arpigny, C.↗

NASA NTRS1991

USSR Space Life Sciences Digest, issue 29

This is the twenty-ninth issue of NASA's Space Life Sciences Digest. It is a double issue covering two issues of the Soviet Space Biology and Aerospace Medicine Journal. Issue 29 contains abstracts of 60 journal papers or book chapters published in Russian and of three Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. A review of a book on environmental hygiene and a list of papers presented at a Soviet conference on space biology and medicine are also included. The materials in this issue were identified as relevant to 28 areas of space biology and medicine. The areas are: adaptation, aviation medicine, biological rhythms, body fluids, botany, cardiovascular and respiratory systems, developmental biology, digestive system, endocrinology, equipment and instrumentation, genetics, habitability and environment effects, hematology, human performance, immunology, life support systems, mathematical modeling, metabolism, musculoskeletal system, neurophysiology, nutrition, personnel selection, psychology, radiobiology, reproductive system, space biology and medicine, and the economics of space flight.

Stone, Lydia Razran↗

NASA NTRS1990

The lunar outpost - Testbed for colonization and extraterrestrial evolution

Three aspects of extraterrestrial habitation are presented with primary focus on lunar habitation. An overview of human experience in low earth orbit (LEO) is given and the establishment of an experience base is discussed. Three primary conditions are listed as crucial requirements for extraterrestrial habitation. These include the construction of artificial environments (AEs); the improvement of AEs so that they are attractive enough for people to want to spend their lives nd eventually bear and raise children in such an environment; and finally, the achievement of self-sufficiency and growth by regenerating consumables and using in situ resources in order to be both cost effective and maximally independent. Regenerative life support, establishment and maintenance of productivity, and the importance of human reproduction in establishing a colony are all discussed in detail. Physiological issues and concerns are considered including hypogravity and radiation physiology.

Harper, Lynn D.↗

NASA NTRS1991

Monte Carlo simulation of ion-neutral charge exchange collisions and grid erosion in an ion thruster

A combined particle-in-cell (PIC)/Monte Carlo simulation model has been developed in which the PIC method is used to simulate the charge exchange collisions. It is noted that a number of features were reproduced correctly by this code, but that its assumption of two-dimensional axisymmetry for a single set of grid apertures precluded the reproduction of the most characteristic feature of actual test data; namely, the concentrated grid erosion at the geometric center of the hexagonal aperture array. The first results of a three-dimensional code, which takes into account the hexagonal symmetry of the grid, are presented. It is shown that, with this code, the experimentally observed erosion patterns are reproduced correctly, demonstrating explicitly the concentration of sputtering between apertures.

Peng, Xiaohang↗

NASA NTRS1991

Lag compensation of optical fibers or thermocouples to achieve waveform fidelity in dynamic gas pyrometry

Fidelity of waveform reproduction requires constant amplitude ratio and constant time lag of a temperature sensor's indication, at all frequencies of interest. However, heat-transfer type sensors usually cannot satisfy these requirements. Equations for the actual indication of a thermocouple and an optical-fiber pyrometer are given explicitly, in terms of sensor and flowing-gas properties. A practical, realistic design of each type of sensor behaves like a first-order system with amplitude-ratio attenuation inversely proportional to frequency when the frequency exceeds the corner frequency. Only at much higher frequencies does the amplitude-ratio attenuation for the optical fiber sensor become inversely proportional to the square root of the frequency. Design options for improving the frequency response are discussed. On-line electrical lag compensation, using a linear amplifier and a passive compensation network, can extend the corner frequency of the thermocouple 100-fold or more; a similar passive network can be used for the optical-fiber sensor. Design details for these networks are presented.

Warshawsky, I.↗

NASA NTRS1991

An improved algorithm for determining neutral winds from the height of the F2 peak electron density

The algorithm of Miller et al. (1986) for determining neutral winds in the thermosphere from the height of the F2 peak electron density is modified, making it possible to reduce the amount of computation time by two thirds. The improved algorithm also provides a more accurate reproduction of h(m)F2 by an ionospheric model than does the original algorithm. The winds obtained from the new algorithm were found to agree well with both the optical and radar measurements conducted at Arecibo on August 17-18, 1982.

Richards, P. G.↗

NASA NTRS1992

Obtaining Patterns Of Holes In Directional Couplers

Technique enables reproduction of pattern of holes in hidden common wall of microwave directional coupler. Talcum-dusting procedure yields pattern of powder on adhesive tape showing sizes of distances between holes. Later, coupler cleaned with water or compressed air. Applicable to other equipment containing inaccessible holes in common wall between adjacent tubes.

Perez, Raul M.↗

NASA NTRS1991

Geostationary Meteorological Satellite-5 (GMS-5)

The Geostationary Meteorological Satellite (GMS-5), which is being developed by the National Space Development Agency of Japan (NASDA), is the fifth geostationary, spin stabilized, weather satellite. Its purposes are to observe cataclysmic events such as hurricanes, typhoons, and regional weather phenomena; to relay meteorological data from surface collection points to the Data Processing Center in Japan; and to transmit processing imaging data for facsimile reproduction. The satellite will be launched from the Tanegashima Space Center (TaSC) in Japan by a type H-II launch vehicle. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas as prime and the 34-m antenna at Madrid as backup support for launch through drift orbit. Maximum support will consist of two 8-hour tracks per station for a seven day period, plus 23 days of contingency support from all complexes. Information is given in tabular form for DSN support, frequency assignments, telemetry, command and tracking station responsibility.

Horii, M.↗